public class AmericanPeople extends People {
   【代码2】 //重写public void speakHello()方法，输出"How do you do"
   【代码3】 //重写public void averageHeight()方法，输出"American's average height:176 cm"
     public void averageWeight() { 
        weight = 75;  
        System.out.println("American's average weight:"+weight+" kg");   
     }
     public void americanBoxing() {
        System.out.println("直拳、钩拳、组合拳");
     }
}